Dipeptide sweeteners, such as the L-aspartic acid derivatives, have received wide acceptance in many applications as an intense sweetener and sugar substitute. These dipeptide sweeteners are characterized by their intense sweetness and their clear initial sweet taste with a lack of any perceived unpleasant or objectionable aftertaste.
The dipeptide sweetener of choice is aspartame (1-methyl-N-L-.alpha.-aspartyl-L-phenylalanine). Aspartame has been successfully used as a sweetener in a number of different applications--liquids, desserts, chewing gum--with no unpleasant or objectionable aftertaste. However, the use of aspartame has been heretofore limited to cold applications or brief moderately heated applications because of the instability of aspartame under elevated temperatures. When subjected to heat, aspartame may hydrolyze to the dipeptide aspartyl phenylalanine (AP) or be converted to diketopiperazine (DKP). DKP can further convert to AP and ultimately the AP converts into its constituent amino acids. AP, DKP and the amino acids produced upon decomposition are not sweet; therefore, the breakdown and/or conversion products of aspartame result in the loss of perceived sweetness.
For these reasons, aspartame has not--to date--been successfully used in applications where a relatively low calorie food product has to be heated, such as baked products. However, aspartame would be an attractive sweetener in these contexts, particularly in dietetic products which contain low or reduced calories. Other artificial sweeteners, e.g. sodium saccharin and calcium saccharin have been used in baked products thereby reducing caloric content, but these sweeteners produce unpleasant aftertastes.
Colliopoulas, et al., in European patent application No. 83106544.6 discloses an allegedly heat stable sweetening composition consisting of a dipeptide sweetener and a polyglucose or polymaltose. Although Colliopoulas et al. reports the increased stability of aspartame in baked applications, it does not refer to the eating quality of such products or to their caloric content, which are computed to be approximately 275 calories/100 g. cake or greater--not a reduced calorie cake.
Vaccarro, in U.S. Pat. No. 4,536,410, discloses a dipeptide sweetener composition which is allegedly heat stable. In Vaccarro, aspartame is combined with a lipid--by alternatively heating and cooling the mixture--to form a gel which is alleged to be thermally irreversible. Although Vaccarro reports, in Example 17, that a reduced calorie cake mix was produced using this gel, overall eating quality of the cake was not discussed. In addition, Example 17 discloses a cake which does not have low sodium or cholesterol levels.
Our invention, however, provides a composition and method well suited for making dietetic food products, such as a cake, as well as other food products. Dietetic products with acceptable taste, eating quality, sweetness, low or reduced caloric content, and low sodium and cholesterol levels can be readily produced.